(1) Field of the Invention
The present invention relates to an improved flexible prophylactic cup particularly adapted for mounting onto a dental hand tool. In particular, the present invention relates to a screw assembly with an inletted head for mounting a molded prophylactic cup onto a dental hand tool and the shape of the working surface of the cup. The prophylactic cup is preferably molded from a silicone polymer, usually containing a dental cleaning and polishing agent such as pumice, uniformly dispersed throughout the polymer. Silicone polymers are poorly adherent to any surface. Therefore, when pumice is added to the silicone polymer, the strength of the silicone polymer is reduced. This strength reduction is often manifested at the point where the cup is molded to a mounting screw or mandrel. Because of the reduced strength, the torque stress causes the cup to become loose and separate from the mounting screw before the teeth cleaning procedure is completed. The present invention preferably overcomes these inherent drawbacks by providing a number of interconnected inlet portions comprised of channels and grooves through the head of the mounting screw. This greatly increases the bonding surface and the bonding strength between the molded silicone polymer and the mounting screw and provides for the bonding to be achieved by mechanical retention.
(2) Prior Art
The prior art has described various types of dental instruments for cleaning stains and plaque from teeth and gingival crevices Some of the prior art devices use a prophylactic cup or a polishing cup mounted on a dental handpiece. Prophylactic cup paste is usually repeatedly applied to the cup in use. The polishing cup can be supplied with a dental cleaning paste that is contained in the dental handpiece and pumped through a channel in the polishing cup to the teeth. U.S. Pat. Nos. 3,977,083 to Leslie et al and 3,977,084 to Sloan shows this type of device. The dental handpieces in these devices are not disposable as in the present invention and must be sterilized between patients.
U.S. Pat. No. 3,789,462 to Riech shows a prophylactic cup that is formed from an elastomeric urethane polymer filled with pumice or other abrasive agents. This device does not require a dental paste because the abrasive pumice is evenly dispensed throughout the elastomeric material. The polyurethane polymer bonds well to the screw; however, this device is used at the expense of the health and safety of the patient because of the toxic nature of urethane materials. Also the shape of the cup is not optimal for cleaning teeth.
The prior art has also shown rotatable disks with embedded abrasive material, rotatable brushes that require an abrasive to be added to the brushes and various shapes of rigid tools that are used for dental hygiene. Illustrative of these prior art devices are U.S. Pat. Nos. 1,451,993 to McLellan; 1,520,491 to Weissleder; 1,620,990 to Brothers; 2,093,007 to Chott; 3,091,033 to Ellman; 3,985,147 to Ricketts et al; 4,335,731 to Bora, Jr.; 4,381,792 to Busch, Jr. et al and 4,601,661 to Du Be et al.